text: Steam locomotives usually do not have condensers so the feedwater is not recycled and water consumption is high.  The use of deionized water would be prohibitively expensive so other types of water treatment are used.  Chemicals employed typically include sodium carbonate, sodium bisulfite, tannin, phosphate and an anti-foaming agent.
  Treatment systems have included:
  * Alfloc, developed by British Railways and Imperial Chemical Industries 
  * Traitement Integral Armand (TIA), developed by Louis Armand
  * Porta Treatment, developed by Livio Dante Porta